It is highly important that your data centres have the appropriate power supply.
TIA-942 was introduced in 2005 with the intention of addressing data centre infrastructure. The document sets out 4 levels of power availability, ranging from:-

Tier 1 – 99.671% availability – Single distribution path – no equipment redundancy
Tire 2 – 99.741% availability – Single distribution path – n+1 equipment redundancy
Tier 3 – 99.982% availability – Dual distribution paths – n+1 equipment redundancy
Tier 4 – 99.995% availability – Dual systems, both active – n+1 equipment redundancy

We have designed and built data centres up to tier 4 standard, incorporating multiple redundant power supplies. However, most tend to be a tier 2 system but with added distribution paths to increase the resiliency of the site.

Interruption of electrical supply to a data centre can be the result of a number of incidents, some planned and others unplanned.

One of our Cemex sites were notified of an impending substation shut down due to maintenance, the site was maintained throughout this period with minimal disruption to services throughout the period.

Other power disruptions can occur without notice and as such backup measures need to be in place to prevent disruption to the data centre.

Short disruptions in power can be dealt with a UPS system, however longer power cuts will need generator backup.

Up to 48 hours of fuel will be typically stored on site within the generator base tank as well as separate remote fuel tanks, with a 24 hour guaranteed fuel delivery the data centre could remain operating through extended periods of disruption.

The resilience of the data centre to equipment failure may be improved by including multiple electrical paths and redundant equipment.

A tier 2 facility will have an additional n+1 UPS and generator that will operate in the event of equipment failure or planned maintenance.

A tier 3 facility will have n+1 UPS and generator with multiple electrical paths that will also allow for switchboard failure or maintenance.

A tier 4 facility will have 2 independent supply paths each with n+1 generator and UPS support.